1-alkyl-4-(meta-hydroxyphenyl)-piperidyl-(4)-alkylketones and their production



NITED STATES ATENT QFFHCE 1-ALKYL-4- (META-HYDROXYPHENYL) PI- PERIDYL- (4) -ALKYLKETONES AND THEIR PRODUCTION Karl Miescher, Riehen, and Hans Kaegi, Basel, Switzerland, assignors to Ciba Pharmaceutical Products, Incorporated, Summit, N. J., a corporation of New Jersey 1 No Drawing. Application May 7, 1945, Serial No.

592,535. In Switzerland June 25, 1943 7 Claims. 1 This application is a continuation-in-part of our copending application, Serial number 530,- 742, filed April 12, 1944, now Patent 2,486,792.

The object of the present invention is a process of preparing 4-ary1-piperidine-4-alkyl ketones.

2 ene-l :Z-dibromide, propylene-1:2 chloro bromide, butylene-1:2 or 2:3-dibromide, c-chloroethanol-p-toluene-sulfonic acid ester, glycol-dipara-toluene sulfonic acid ester or propane-1:2- diol-di-Inethane sulfonic acid-ester.

These 4-aryl-piperidine-4-alkylketones are ob- 6 The reaction itself is carried out in the pretained by causing u-arylated tertiary y-amino sence of acid binding agents. For this purpose fatty acid nitriles to react With reactive esters the following b ed: sodium, potassium, of alkylene-l:2-dicls in the presence of acid bindlithium, calcium, as such or in a form of their agents in one or more step Converting the 10 alcoholates, amides, hydrides or hydrocarbons, nitrile r up in t -ary -p p ar o yas e. g., potassium-tertiary butylate, potassiumlic acid nitriles obtained into a keto group, and, tertiary amylate, sodium amide, sodium hydride, f d d, spl tin ff a y p as of h butyl-lithium, phenyl-sodium or phenyl-lithium. action radicals Which e u t ble fo be ng It is advantageous to use inert solvents such as, eliminated and are attached to the cyclic nitro- 5 e. g. ether, benzene, toluene, xylene or hexane and to work in the presence of indifferent gases As starting products there are used therefore such as nitrogen. According to the reactivity a-arylated tertiary y-amino fatty acid nitriles of the components, the reaction is carried out in Which the y group m y e epresented, e. a. with cooling, at ordinary temperature or even by a substituted or unsubstituted phenyl 01' with heating. It is possible to close the ring naphthyl group, the substituents being in any in one or more steps. position. The aliphatic radical can be straight The nitrile group of the compounds thus obor branched or even arranged as part of a ring. tained may be converted into a keto group. The For example the following compounds can be nitrile group can also be converted into an amide used: a-phenyl-y-(methyl-benzyl-amino)-butyr- 25 group in known manner either directly or after i0 acid nitrile. -D e y -'y ethy1- or diethylconversion into the carboxyl group. The obtained amino) -butyric acid nitrile, a-(benzyl-oxyor piperidines contain a quaternary ring nitrogen acyloxy-phenyl)w-( methyl-benzyl-amino) bu atcm. They can be converted into such with tyric acid nitriles, u-(o-anisyl)-y-(methylditertiary nitrogen, for example, by splitting ofi phenylmethyl-amino)-butyric acid nitrile, or-(III- 30 alkyl halide by heating. The conversion also anisyl)-y-dimethylamino-butyric acid nitrile, usucceeds easily if there is as a radical attached phenyl -'y- (methyl-benzyl-amino)-valeric acid to the nitrogen, e. g. a mono-, dior tri-aryl nitrile, a-naphthyl-y-(dimethyl-amino)-butyric methyl group which can be removed, amon acid nitrile 0 -l e y y en ylothers under the influence of catalytically actiamino) cyclohexyll acetic acid nitrile. The 35 vated hydrogen or by treatment with e. acids above mentioned starting products are in some or by heating. This conversion can moreover instances known or can be obtained in a known he carried out at any desirable phase of the remanner. action.v If the aryl radical of the reaction prod- For the reaction with the above nitriles the nets contains one or several substituted hydroxyl following reactive alkylene-lz2-dio1 esters, for groups, these can be converted into unsubstituted example, may be used: ethylene-dibromide, ethylene-chloro-bromide, ethylene-diiodide, propylhydroxyl groups in the usual manner, for example by treatment with glacial acetic hydrohalic acids.

3 The process is further elucidated by formulae on the basis of the following scheme:

N f Hs CH:

VI VII R=hydrocarbon radical capable of being split off R=alcohol radical or substituted or unsubstituted amino group R=hydrocarbon radical According to the present process a large number of piperidine compounds can be obtained. As a result of the considerable possibilities of variation, numerous new compounds are accessible in addition to known compounds. Of particular interest is the discovery that, for example, the reaction of ethylene-dibromide with a compound of the Formula I according to the above scheme leads pre-eminently to cyclic compounds and not to acyclic ones. It also seems surprising, for example, that the conversion of a compound of the Formula II, in which R represents a hydro- Example 1 52.8 parts of a-phenyl-y-(methyl-benzyl-amino) -butyric acid nitrile (B. P. 0.1 mm. 153-155- 0., prepared from benzyl cyanide and ,B-chloroethylmethyl-benzyl-amine in the presence of sodium amide) in 200 parts of ether are added drop by drop while stirring to parts of powdered sodium amide which is suspended under nitrogen in 200 parts of ether. When the reaction is complete,

" considerable heat.

the mixture is stirred for an hour, then 300 parts of ether are added, the whole is cooled with ice and 40 parts of ethylene-dibromide are added. Stirring is then resumed for an hour under ice cooling, for another hour at room temperature and for 4-5 hours by heating to 40 C. A thick suspension of salts is formed. This is decomposed with water and aqueous hydrobromic acid is added until the mixture shows an acid rereaction. The 1:1-methyl-benzyl-4:4-phenylcyano-piperidinium bromide formed, which is difiicultly soluble in water, is precipitated and isolated by filtration with suction and washing with ether and water. It still contains some hydrobromide of the starting product as well as other by-products. For purification the crude bromide is dissolved in the just necessary quantity of boiling water, soda solution is added and the mixture is allowed to cool. The thick mass is thoroughly shaken with ether which dissolves the non-quaternary bases. After filtration with suction and washing with water and ether the remaining salt is recrystallized from the fourfold quantity of boiling water. Thus a good yield of the pure 1 1-methyl-benzyl-4 l-phenyl-cyanopiperidinium-bromide is obtained in two crystalline forms, as glossy flakes and as white aggregates, which cannot be converted into each other and probably represent cis-trans-isomers. The melting point of both bromides is not sharp and lies at about 245 to 260 C.

If the bromide is shaken in aqueous alcoholic solution with hydrogen and palladium black, 1-methyl-4-phenyl-4-cyano-piperidine is formed almost quantitatively from both crystalline forms, in addition to toluene. The 1-methyl-4:4-phenyl-cyano-piperidine can be saponified and esterified with ethanol in known manner to produce 1 -methyl4 4-pheny1-carbethoxy-piperidine.

The same substance is obtained, if the quaternary bromide is heated with sulfuric acid of about to per cent strength, the resulting acid esterified with ethanol and the product subsequently hydrogenated.

Example 2 A solution of 52.8 parts of oc-IJhBIlYl-y- (methylbenzyl-amino)-butyric acid nitrile in 200 parts of ether is added drop by drop to 10 parts of powdered sodium amide in 200 parts of ether. After stirring for 1 hour, a solution of 50 parts of propylene-lzZ-dibromide in parts of ether is added. The ether slowly reaches its boiling point, the boiling temperature being maintained for 2 hours by external heat. In this reaction only sodium bromide is precipitated and no quaternary salt. On decomposition of the reaction product with water an ethereal and an aqueous layer are obtained which are easily separated. After evaporation of the ether an oil is obtained from the ethereal layer which after prolonged heating on the water bath becomes solid and insoluble in ether. Obviously the formation of the ring of the quaternary bromide occurs only after applying The product is triturated with ether, filtered with suction and thus the 1:1- methyl benzyl 2-methyl-4:4-phenyl-cyano-piperidinium bromide is obtained. The product is dissolved without further purification in the tenfold quantity of alcohol of 50 per cent strength and after the addition of about 2 per cent of a platinum catalyst shaken up with hydrogen. When no more hydrogen is absorbed, the whole is filtered with suction, a greater part of the filtrate is evaporated and the residue is rendered alkaline and extracted with ether. (Sn-evaporation the ether leaves behind an oil, which boils under a pressure of 0.07 mm. at '-107-1 l-C. This is the 1 :2 dimethyl 4:4 phenyl-cyano-piperidine. It can be saponifiedand esteri'fiedaccording to known methods whereby with the use of ethyl alcohol 1:2 dimethyl 4:4 pheny1-carbethoxy-piperidine is obtained which forms an oil boiling at 105-109" C. under a pressure of 0.15 mm.

As starting product oz-(IIl-IlitIO-DhGHYl) -'y- (methyl-benzyl-amino) -butyric acid nitrile, e. g. can also be used and the nitro group in the resulting compounds converted in usual manner into an aminoor a hydroxygroup.

The 1 :2 dimethyl 4:4-phenyl-cyano-piperidine obtained can further be COIIVGItEd'iI'l known manner into the 1:2-dimethyl4-phenyl-piperidine-4-carboxylic acid amide by partial saponification. For the manufacture of amides the obtained nitrile can also be completely saponified, the acid thus obtained converted into the acid chloride by treatment for example with thionyl chloride, and the acid chloride reacted with ammonia or amines. Thus, from the corresponding acid chloride and diethylamine there is obtained 1:2-dimethyl 4 phenylpiperidine-4-carboxylic acid diethylamide.

These amides can also be obtained by converting the above obtained 1:1-methyl-benzyl-2- methyllz l-phenyl-cyano piperidinium bromide into the amides and subsequently splitting off the benzyl group.

Example 3 A solution of 65 parts of u-phenyl-y-(diethylamino) -butyric acid nitrile in 200 parts of absolute ether is added drop by drop to 14 parts of powdered sodium amide in 300 parts of ether. After an hours stirring 300 parts of ether are added, the mixture cooled with ice and then 60 parts of ethylene-dibromide added. Stirring is carried out for one hour at ice temperature, for another hour at room temperature and for four to six hours at the boiling temperature of the ether. The very consistent reaction massis'separated by filtration with suction'washedwith ether and dried. 125 parts of a white readily watersoluble salt mixture are obtained which consists, in addition to sodium bromide, chiefly of 1:1- diethyl-4 4-phenyl-cyano-piperidinium bromide. By treating the salt mixture with alcohol, the insoluble sodium bromide contained therein can be eliminated. If the piperidinium bromide or the hydroxide which can be prepared from it, is heated in the vacuum, there is produced by cleavage of ethyl bromide or ethyl alcohol, respectively. the 1-ethy1-4:4-phenvl-cyano-piperidine which is an oil boiling at 110-112 C. under a pressure of 0.05 mm. It can be saponified and -esterified in known manner orconvertedby means of-Grignards compounds into l-ethyl-l-phenyl-piperidyl- (4) -ketones. such as 1-ethyl-4-phenyl-piperidyl-(4)-ethylketone (oil of boiling point 100 C. under 0.1 mm. pressure).

These ketones can also be obtained if the 1:1- diethyl-4:4-phenyl-cyano piperidinium bromide is treated with Grignards compounds and the bromine and one of the ethyl groups are subsequently split ofi.

Example 4 18.8 parts of -m-'phenyl -'y (dimethylamino) butyric acid-nitrile (oil of boiling point 158-"1 60 C. under 1? mm. pressure, obtained from benzylcyanide, p-dimethylaminoethel chloride and sodium amide) are dissolved in 100 partsby volume of ether and allowed to flow into 5 parts of pulverized sodium amide in '80 parts by volume of ether. When the reaction is-co-mplete, the whole is cooled to 5 18.8 parts of ethylene-dibro-- mide'in 50 parts'by volume of ether are added, and the further procedure is as indicated in Example 3. The 1:1-dimethyl-4:4-phenyl-cyanopiperidinium bromide can be isolated from the suctionefilteredvcrystal magma by treatment with alcohol .in .laminae .of melting point 305-315 C. (with decomposition). By thermal decomposition of this substance or also of the crude crystal magma the 1-methyl-4 4-phenylcyano-piperidine described in Example 1 is obtained in good yield.

E'Ymmple 5 6 parts of pulverized sodium in parts by volume of toluene are converted into the phenyl sodium compound with 13.2 parts of cholorobenzene. .22 parts of c-(meta-methoxyphenyhy-(dimethylamino)-butyric acid vnitrile .(yell-owish oil of boiling point 184-186 C. under 14 mm. pressure, prepared from meta-methoxy-benzylcyanide, fl-dimethylaminoethylchloride and sodium amide) in 30 partsbyvolume of toluene are added drop by drop. After stirring for 3 hours a yellow green precipitate has separated. 18:8 parts of ethylene-dibromide-in parts by'volwine of toluene are added in drops at +10 C. to maximally 40 C. and the whole is further stirred for 15 hours. By filtering oil and washing with ether there are obtained 45 parts of a nearly white powder. This yields on distillation 12 mm. 270-350 C. (bath temperature) the l-methyl- 4 4- (meta-methoxyphenyl-cyano-piperidine as a yellowish oil of boiling point 196-197 C. under 12 mm. pressure which solidifies on standing and then melts at about 40 C., methylbromide being split off from the quaternary compound.

On heating this nitric with methanolic caustic soda solution to -200 C., there is obtained the .1-methyl-l (meta-methoxyphenyl) -piperidine-l-carboxylic acid of melting point 322- 323 C. (with decomposition) which yields the 1- methyll-(meta-methoxyphenyl) piperidinelcarboxylic acid ethylester on esterification with alcohol (oil of boiling point -497 C. under 12 mm. pressure). The hydrochloride of this ester melts at FIE-176 C.

When heating the above l-methyll-(metamethoxyphenyl) ipiperidine-4-carboxylic acid with glacial acetic hydrogen bromide, there is formed the 1methyl-4-(meta-hydroxyphenyl)- piperidine-e-carboxylic acid (brownish needles of melting point 289-285 (3.). On esterification the l-methyl-l- (meta-hydroxyphenyl) -pi1:-eridine-4-carboxylic acid ethylester is obtained therefrom which yields a hydrochloride of melting point 16,6-167 C.

When saponifying the l-methyl-lA-(metamethoxyphenyl)-cyano-piperidine under mild conditions with methyl. alcohol caustic soda solution (2 hours at ISO-170C), there isobtained the 1-methyl4- (meta-methoxyphenyl) -piperidinel-carboxylic acid amide in the form-of crystals which melt at 133-435 C. with decomposi tion.

If 1- methyl-4-meta-methoxyphenyl-'4-cyanopiperidineiscaused to react with Grignard'compounds, thecorresponding ketones are obtained. With .n-pr opylemagnesium bromide there can be obtained l-methyll (meta-methoxyphenyl) -pi- 7 peridyl-(4)-n-propylketone (hydrochloride of melting point 125-127 C.), from which the 1- methyl-l- (meta hydr oxyphenyl) -piperidyl-4-npropyl-ketone (a feebly yellowish oil) is obtained by boiling with hydrobromic acid. l-methyll- (m-hydroxyphenyl) -piperidyl-(4=) ethyl-k-etone hydrobromide of melting point 190191 C. is obtained in a corresponding manner with ethylmagnesium bromide.

Example 6 When replacing in Example 1 the 52.8 parts of a-phenyl-y-(methyl-benzyl-amino) -butyric acidnitrile by 58.8 parts of ca- (ortho-mcthoXyp-henyl) v-(rnethyl-benzylamino)-butyric acid-nitrile (a thick oil of boiling point 165-166" C. under 0.06 mm. pressure, prepared from ortho-methoxybenzylcyanide with p-chloroethyl-methylbenzylamine in the presence of sodium amide), there is obtained the lzl-methyl-benzyllz l-(orthomethoxyphenyl)-cyano-piperidinium bromide in white crystals of melting point 203-204" C.

If this bromide is shaken in an aqueous alcoholic suspension with hydrogen and palladium, it takes up 1 mol of hydrogen and goes into solution. When filtering the solution to remove the p-alladium and concentrating, the hydro-bromide of the l-methyl-dvi- (ortho-methoxyphenyl)- cyano-piperidine crystallizes in large brilliant crystals of melting point 262-264 C. The free base forms in ether rather sparingly soluble laminae of melting point 98-99 C.

Example 7 A solution of 436 parts of a-(meta-methoxyin 1000 parts by volume of ether is gradually added, while stirring, to a suspension of 100 parts of pulverized sodium amide in 2000 parts by volume of ether. The sodium amide enters into solution with evolution of ammonia, but the sodium compound of the a-(meta-methoxyphenyl-v-(dimethylaminol -butyric acid nitrile is soon precipitated as a sandy crystal powder. In order to complete the reaction the whole is boiled for 1 hour under reflux. After cooling to C. or slightly below 0 C. a solution of 470 parts of p-toluene sulfonic acid-,c-chlorohydrin ester in 1000 parts by volume of ether is added in such a manner that the temperature does not exceed 0 C. After further stirring for hour the Whole is suction-filtered to remove the precipitated sodium-toluene sulfonate. The condensation product corresponding to the Formula 11a is found in the filtrate. Already on allowing this ether solution to stand gradual ring closure to the quaternary base occurs, i. e. to the lzl-dimethyl (meta methoxy phenyl) l cyanopiperidinium chloride, which is left behind as a hard, white crystal cake on evaporating the ether solution. t can be recrystallized from alcohol. When heating this salt to 230-250 C. under 12 mm. pressure, it is decomposed without melting, and the l methyl 4 (m methoxyphenyl) -4-. cyano-piperidine described in Example is distilled in theoretical yield which solidifies immediately.

By reacting 230 parts of this nitrile with a Grignard solution prepared from parts of magnesium and the necessary quantity of bromomethyl, there is formed l-methyl-4-(methoxyphenyl) piperidyl (4) methylketone which is converted into the l-methyll-(m-hydroxyphenyl) -piperidyl-(4) -methyl-ketone of melting 8 point 158-159 C. by boiling with hydrobromic acid and. subsequently treating with ammonia.

What we claim is:

1. In a process for the manufacture of a 4- aryl-piperidyl-( l)-alkyl-ketone, the step of re acting an a-arylated tertiary 'y-amino-butyric acid nitrile of the formula wherein Ar is a member selected from the group consisting of unsubstituted aryl and aryl substituted by alkoxy, R1 is lower alkyl and R2 is a member selected from the group consisting of lower alkyl and aralkyl, with an alkylene-1:2 diol ester of an organic sulfonic acid in the presence of a substance forming a metal compound of the said nitrile whereb a quaternary 4t l-aryl-cyano-piperidine is formed.

2. In a process for the manufacture of a 4- phenyl-piperidyl-( l)-alkyl-ketone the step of reacting a tertiary y-amino-a-phenyl butyric acid nitrile of the formula N l z wherein Ph is a phenyl radical containing in at least one of the positions ortho and meta an alkoxy group, R1 is lower alkyl and R2 is a member selected from the group consisting of lower alkyl and aralkyl with an alkylene-lzZ-diol ester of an organic sulfonic acid in the presence of a substance forming a metal compound of the said nitrile whereby a quaternary 4:4-alkoxypenyl-cyano-piperidine is formed.

3. In a process for the manufacture of a 4- phenyl-piperidyl- (4) -alkyl-ketone, the step of reacting the sodium compound of a-(meta-meth oxy-phenyl) -y-(dimethylamino) -butyric acid nitrile of the formula OCH:

N Cfis CHa with the fi-chloro-ethanol-Y-toluene-sulfonic acid ester whereby 1 l-dimethyll- (meta-methoxyphenyl) -2-cyano-piperidinium chloride is formed.

4. A 1 lower-alkyl-4-(meta hydroxyphenyl) piperidyl-(4)-a1kyl-ketone of the formula wherein each of R and R1 represents a lower 1 alkyl group.

10 3. I-methyi 4-(meta hydroxyphenyl) -piperi- REFERENCES CITED dyl'(4)'methyl'ketone of the formula The following references are of record in the file of this patent: Q o-on. UNITED STATES PATENTS Number Name Date H2O CH1 2,167,351 Eisleb July 25, 1939 5 5 2,403,903 Bergel et a1 July 16, 1946 FOREIGN PATENTS 6H1 Number Country Date 6. 1 methyl 4-(meta hydroxyphenyl) -piper- 501,135 Great Britain Feb. 21, 1939 idy1-(4)-ethy1-ketone of the formula, 218,517 Switzerland Apr. 1, 1942 OTHER REFERENCES Koelsch, J. Am, Chem. 800., 65, 2093-2095, 1943.

Chem. Soc. Journ, pages 261-269, 1944 mg Archiv. for Exp. Path. Pharm, 196, 127-129. 11 511 f/ '7. l-methyl 4 -(meta-hydroxypheny1) -piperidyl-(4) -propy1-ketone of the formula CO-CsH1 @v 250 cH, H56 (13H: f/

KARL MIESCHER. HANS KAEGI.

Certificate of Correction Patent No. 2,486,794 November 1, 1949 KARL MIESCHER ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 26, for a-phenyl-'y(din1ethylread a-phenyl-y-(dimethylq column 6, line 2, for -dirnethylaminoethel read B-dimethylaminoethyl; line 36, before the numeral 12 insert an opening parenthesis; line 37, before the Word bath strike out the opening parenthesis; line 38, after methoxyphenyl insert a closing parenthesis, line 43, for nitric read nitrile; column 8, line 43, for penyl read phenyl;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office. Signed and sealed this 28th day of March, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commisszoner of Patents. 

